The shows made synchronized YouTube videos that demonstrate how water drains in Huntsville, Ala. and Sydney, Australia.

(To sync them, play the video on the left up to the point where it says, "synchronize videos." Then start playing the other one. Once that video shows "synchronize videos," play the other vid once more where you paused it.)

SmarterEveryDay's Destin Sandlin and Veritasium's Derek Muller didn't just stop at flushing toilets or watching water flow down drains.

They both filled kiddie pools full of water and then drained them, putting food colouring in each to see how the water flows out.

Sure enough, they proved Lisa Simpson's theory. The water in Alabama flowed counter-clockwise, and in Australia it drained out in a clockwise direction.

Now, if only we could apply this kind of scientific rigour to other questions.